Implantable drug delivery or infusion devices and/or systems are commonly used, for example when chronic administration of a pharmaceutically active agent or therapeutic substance to a patient is required. An implantable infusion pump-catheter delivery system may be preferred when it is important to deliver the agent to a specific site or when the agent must be administered to spaced sites in tightly controlled, yet minute dosages.
Typically, an implantable therapeutic substance delivery device has a reservoir for holding a supply of therapeutic substance awaiting delivery to a delivery site in the patient. A pump may be fluidly coupled to the reservoir for creating fluidic pressure to facilitate delivery of the therapeutic substance to the patient. A catheter provides a pathway for delivering the therapeutic substance to the delivery site in the patient.
All parts of the therapeutic substance delivery device/system need to operate adequately to ensure proper functioning of the device/system. While perhaps the least complex, catheters can have and can develop operational problems.
Sometimes catheters in such delivery systems can become obstructed or clogged. A partial or complete blockage could prevent the therapeutic substance from reaching the delivery site in the patient or, in the case of a partial obstruction, could prevent an adequate supply of the therapeutic substance from reaching the delivery site in the patient.
Catheters can also leak due to cuts, tears, etc. A leak, small or large, can also prevent the therapeutic substance from reaching the delivery site in the patient. A leak can result in a double problem. In addition to the lack of therapeutic substance supplied to the delivery site of the patient, the therapeutic substance could be dispersed elsewhere in the body of the patient which may create further issues.
When catheters become clogged or leak and the infusion pump continues to deliver drug, a patient's well being may be placed in danger.
However, it has been difficult to detect the malfunction of a catheter. For example, if the catheter has a leakage, the implantable drug delivery device could continue to delivery therapeutic substance and there may be no way to know that the therapeutic substance was not reaching the desired delivery site. The patient may not receive the benefit of the therapeutic substance but might not know why. As another example, if the catheter has an obstruction, the implantable drug delivery device might cease to deliver the therapeutic substance. But it may be difficult to know why the failure occurred. The failure to deliver might have been caused by other factors, such as power failure, pump failure or an empty reservoir.
If a catheter malfunctions, it is desirable to know so that appropriate corrective action can be taken.